Occupant knee protection system for vehicle and inflating and deploying method

ABSTRACT

An occupant knee protection system for a vehicle ( 10 ) has an airbag ( 11 ), which is folded and stored in a part of a vehicle, inflate and deploy in front of the occupant&#39;s knees by gas supplied from an inflator ( 12 ), so as to protect the occupant&#39;s knees. The airbag ( 11 ) has in its inside a tether ( 11   c ) (gas flow dividing portion whose front and rear end portions are connected to front and rear walls ( 11   a   , 11   b ) of the airbag ( 11 ), both walls being arranged in a longitudinal direction of the vehicle, so as to appropriately regulate a longitudinal thickness (D) of the airbag ( 11 )) for dividing a gas flow from the inflator ( 12 ) in right and left directions of the vehicle.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an airbag system and inflating and deployingmethod of the airbag, provided in a vehicle, more particularly to anoccupant knee protection system for a vehicle (knee airbag system) whichprotects occupant's knees by inflating and deploying an airbag(sometimes called as a gas bag), which is folded and stored in a part ofthe vehicle, in front of the occupant's knees by gas supplied from aninflator.

2. Description of the Related Art

A related art of the occupant knee protection system for a vehicle isdisclosed in, for example, the Japanese Patent Laid-Open Publication No.11-321539. This publication discloses an occupant knee protection systemfor a vehicle in which opposed wall portions (front wall portion andrear wall portion) of an airbag are connected via connecting means so asto suppress the shape change of the airbag in a case the occupant'sknees smash into the airbag.

SUMMARY OF THE INVENTION

According to the aforementioned related art of the occupant kneeprotection system for a vehicle, the shape change of the airbag when theoccupant's knees smash into the airbag can be suppressed by theconnecting means provided in the airbag. However, since the airbagitself inflates in a spherical shape at the time of inflation anddeployment, the airbag may be inflated into a large size in between bothknees (between legs) of the occupant, thereby making it difficult forthe airbag to gets in front of both left and right knees of theoccupant.

[Means for Solving Problem]

To solve the problem stated above, the invention is characterized inthat, in the occupant knee protection system for a vehicle whichprotects occupant's knees by inflating and deploying an airbag, which isfolded and stored in a part of the vehicle, in front of the occupant'sknees by gas supplied from an inflator, gas flow dividing portion fordividing a flow of the gas supplied from the inflator in right and leftdirections of the vehicle is provided inside the airbag.

In this case, it is preferable that the gas flow dividing portion isformed in a predetermined length in a longitudinal direction of thevehicle, and both front and rear end portions of the gas flow dividingportion are connected, respectively, to front and rear walls of theairbag that are arranged in the longitudinal direction of the vehicle.In addition, the gas flow from the inflator runs in a vertical directionof the vehicle, and therefore the gas flow dividing portion ispreferably formed in a mountain-like shape that protrudes against thegas flow from the inflator. Furthermore, it is preferable that the gasflow dividing portion has communicating portion for communicatingbetween. one area and the other area within the airbag, both areas beingseparated by the gas flow dividing portion.

With the occupant knee protection system for a vehicle according to theinvention, introduction of the gas can be facilitated while distributingthe gas within the airbag in left and right directions of the vehicle bythe gas flow dividing portion. As a result, inflation and deployment ofthe airbag at its center portion (airbag inflation in a spherical shape)is suppressed, thereby improving the inflation and deploymentperformance at both end portions of the air bag in a lateral directionof the vehicle. This arrangement allows the airbag to get in front ofthe occupant's knees, making it possible to appropriately protect theoccupant's knees.

In the occupant knee protection system for a vehicle according to theinvention, in addition that the introduction of the gas in left andright directions of the vehicle can be facilitated by the gas flowdividing portion , a longitudinal thickness of the airbag in an inflatedand deployed state can be regulated appropriately (in a predeterminedlength). Therefore, the airbag inflation and deployment can berestricted such that the airbag is not inflated more than required in alongitudinal direction of the vehicle, enabling the airbag to get infront of the occupant's knees easily.

Furthermore, in the occupant knee protection system for a vehicleaccording to the invention, the gas supplied from the inflator can bedistributed quickly and evenly in right and left directions by the gasflow dividing portion. As a result, the inflation and deployment of theairbag in left and right directions in equal amount can be facilitated.In addition, while facilitating the performance of the inflation anddeployment of the airbag in right and left directions, the occupant kneeprotection system for a vehicle according to the invention also enablesimprovements of the inflation and deployment performance of the entireairbag and an airbag shape retention effect.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view which schematically shows one embodiment of anoccupant knee protection system for a vehicle according to theinvention;

FIG. 2 is a perspective view showing relationships of a panel, abracket, an instrument panel reinforcement, and the occupant kneeprotection system for a vehicle in FIG. 1;

FIG. 3 is a perspective view of an inflated and deployed state of anairbag of the occupant knee protection system for a vehicle in FIG. 1;

FIG. 4 is a longitudinal center sectional view from the rear whichschematically shows a first modified embodiment of the occupant kneeprotection system for a vehicle according to the invention;

FIG. 5 is a longitudinal center sectional view from the rear whichschematically shows a second modified embodiment of the occupant kneeprotection system for a vehicle according to the invention;

FIG. 6 is a perspective view, equivalent to FIG. 3, which schematicallyshows another embodiment of the occupant knee protection system for avehicle according to the invention;

FIG. 7 is a longitudinal center sectional view of the embodiment shownin FIG. 6 from the rear;

FIG. 8 is a longitudinal center sectional view of the embodiment shownin FIG. 6 from the side; and

FIG. 9 is a longitudinal center sectional view from the rear whichschematically shows a second modified embodiment of the occupant kneeprotection system for a vehicle in which an inflator is provided outsidethe airbag.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Exemplary embodiments according to the invention will be describedhereinafter with reference to accompanying drawings. FIGS. 1 to 3 showone embodiment of an occupant knee protection system for a vehicleaccording to the invention. An occupant knee protection system (kneeairbag system) 10 in the embodiment is assembled to an instrument panelreinforcement 23 via a panel 21 and a bracket 22 at approximately thesame height as a knee B of an occupant A. Furthermore, the occupant kneeprotection system 10 is provided with an airbag 11 which inflates anddeploys in front of the knee B of the occupant A, and an inflator 12which supplies gas to the airbag 11.

The airbag 11 is made of a woven fabric and is folded and stored insidean instrument panel 24. The airbag 11 intervenes between the panel 21and the knee B of the occupant A at the time of inflation and deploymentas shown in FIG. 1 so as to protect the knee B of the occupant A.Furthermore, as shown in FIG. 3, the airbag 11 has in its inside atether 11 c for connecting a front wall 11 a and a rear wall 11 b of theairbag 11 that are arranged in a longitudinal direction of the vehicle,and is supported on the panel 21 via the front wall 11 a.

The tether 11 c is a rectangular woven fabric formed in predeterminedlengths of La and Lb in longitudinal and lateral directions of thevehicle, respectively. The front and rear end portions of the tether 11c are connected to (for example, sewn to) the front and rear walls 11 a,11 b of the airbag 11 that are arranged in the longitudinal direction ofthe vehicle. The tether 11 c extends in longitudinal and lateraldirections above a gas supply hole 12 a of an inflator 12, so as to forma pair of inflating chambers R1, R2 arranged one on top of the otherwithin the airbag 11, both chambers being communicated with each otherat the right and left end portions of the tether 11 c. In addition, thetether 11 c functions as a connecting means for connecting the front andrear walls 11 a, 11 b of the airbag 11 that are arranged in thelongitudinal direction of the vehicle, and also as gas flow dividingportion for dividing the gas flow from the inflator 12 in right and leftdirections of the vehicle.

The inflator 12 injects and supplies gas into the airbag 11 upon afrontal collision of the vehicle, and is incorporated in the airbag 11to be supported on the panel 21 together with the airbag 11.Furthermore, the inflator 12 has the gas supply hole 12 a for injectingand supplying the gas towards a bottom face of the tether 11 c (i.e.injecting the gas upward).

In the occupant knee protection system 10 configured as described aboveaccording to the embodiment, the airbag 11 is normally stored inside theinstrument panel 24 in a multi-folded state, and covered by a lowerportion of the instrument panel 24. Also in this embodiment, gas issupplied from the inflator 12 into the airbag 11 that is stored in thefolded state when the acceleration detected by a relevant sensor (notshown) upon the frontal collision of the vehicle reaches or exceeds aset value. As a result, the airbag 11 inflates and deploys by thesupplied gas, so as to intervene between the panel 21 and the knee B ofthe occupant A, thereby protecting the knee B of the occupant A.

Meanwhile, according to this embodiment, introduction of the gas can befacilitated while distributing the gas in right and left directions ofthe vehicle by the tether 11 c within the airbag 11. This suppressesinflation and deployment of the airbag 11 at its center portion(inflation of the airbag 11 in a spherical shape), and thus theinflation and deployment performance of the airbag 11 at both endportions in the lateral direction of the vehicle is improved.Consequently, the airbag 11 is made to promptly get in front of the kneeB of the occupant A, making it possible to appropriately protect theknee B of the occupant A.

In the occupant knee protection system for a vehicle 10 according tothis embodiment, in addition that the introduction of the gas from theinflator 12 in right and left directions of the vehicle can befacilitated by the tether 11 c, a longitudinal thickness D of the airbag11 in the inflated and deployed state can be regulated appropriately (ina predetermined length La). As a result, the airbag inflation anddeployment is restricted such that the airbag 11 is not inflated morethan required in the longitudinal direction of the vehicle, thusenabling the airbag to get in front of the knee B of the occupant Aeasily.

In the aforementioned embodiment, the tether 11 c is formed and arrangedwithin the airbag 11 in a tabular shape against the gas flow from theinflator 12. Nonetheless, as illustrated in FIG. 4 or FIG. 5, or FIGS. 6to 8, the tether 11 c may be formed and arranged in a mountain-likeshape which protrudes against the gas flow from the inflator 12. In theembodiments shown in FIG. 4 and in FIGS. 6 to 8, the tether 11 c isformed and arranged in a mountain-like shape which protrudes in aV-shape against the gas flow from the inflator 12. In the embodimentshown in FIG. 5, the tether 11 c is formed and arranged in amountain-like shape which protrudes in a U-shape against the gas flowfrom the inflator 12.

In the occupant knee protection system for a vehicle according to eachembodiment shown in FIG. 4, FIG. 5, and FIGS. 6 to 8, the gas from theinflator 12 can be distributed quickly and evenly in right and leftdirections of the vehicle by the tether 11 c in the airbag 11. Thisfacilitates the inflation and deployment of the airbag 11 in right andleft directions in equal amount.

Furthermore, in the occupant knee protection system for a vehicleaccording to the embodiment shown in FIGS. 6 to 8, the tether 11 c isprovided with three communicating holes 11 c 1 which communicate betweenan inflating chamber (one area) R1 and an inflating chamber (the otherarea) R2 within the airbag 11, both chambers being separated by thetether 11 c. Due to this arrangement, the occupant knee protectionsystem for a vehicle according to this embodiment can facilitate theinflation and deployment performance of the airbag 11 in the lateraldirection, and at the same time, can improve the inflation anddeployment performance of the entire airbag 11 as well as a shaperetention effect of the airbag 11.

In each of the aforementioned embodiments, the inflator 12 is providedin the lower part in the airbag 11 such that the inflator 12 injects andsupplies gas in an upward direction of the vehicle. However, theinflator may be provided in the upper part in the airbag such that theinflator injects and supplies gas in a downward direction of thevehicle. In this case, if the same structure as that in each embodimentin FIGS. 4 to 8 is adopted, the tether is formed and arranged in amountain-like shape which protrudes upward.

Furthermore, in each of the embodiments described above, the inventionis carried out in the embodiment in which the inflator 12 is providedinside the airbag 11. However, as shown in FIG. 9, the invention may becarried out in an embodiment in which the inflator is provided outsidethe airbag, in the same manner as in or with the appropriatemodifications to the aforementioned embodiments.

1. An occupant knee protection system for a vehicle, comprising: aninflator; an airbag which is folded and stored in a part of the vehicle,that is inflated and deployed in front of knees of an occupant by a gassupplied form the inflator for protecting knees of the occupant; and agas flow dividing portion that divides a gas flow from the inflator inright and left directions of the vehicle is provided inside the airbag,characterized in that: the gas flow dividing portion is formed in apredetermined length in a longitudinal direction of the vehicle, frontand rear end portions of the gas flow dividing portion being connectedto front and rear walls, that are arranged in the longitudinal directionof the vehicle, of the airbag, that the inflator is disposed at an upperend portion or lower end portion of the airbag as viewed in the verticaldirection of the vehicle, and that a direction of the gas flow from theinflator is in a vertical direction of the vehicle, and the gas flowdividing portion is formed in a mountain shape which protrudes againstthe gas flow from the inflator.
 2. The occupant knee protection systemfor a vehicle according to claim 1, characterized in that: the mountainshape is formed and arranged so as to protrude in a V-shape.
 3. Theoccupant knee protection system for a vehicle according to claim 1,characterized in that: the mountain shape is formed and arranged so asto protrude in a U-shape.
 4. The occupant knee protection system for avehicle according to claim 1, characterized in that: the gas flowdividing portion is a tether made of a woven fabric.
 5. The occupantknee protection system for a vehicle according to claim 1, characterizedin that: the gas flow dividing portion has communicating portion thatcommunicates between one area and an other area within the airbag, bothareas being separated by the gas flow dividing portion.
 6. The occupantknee protection system for a vehicle according to claim 5, characterizedin that: the communicating portion is a communicating hole provided onthe gas flow dividing portion.
 7. The occupant knee protection systemfor a vehicle according to claim 1, characterized in that: the inflatoris provided inside the airbag.
 8. The occupant knee protection systemfor a vehicle according to claim 1, characterized in that: the inflatoris provided outside the airbag.
 9. An inflating and deploying method ofan airbag of an occupant knee protection system for a vehicle bysupplying a gas from an inflator, comprising the step of: inflating theairbag by the inflator; dividing a gas flow from the inflator in rightand left directions of the vehicle by a dividing portion; and deployingthe airbag characterized by comprising the step of: forming the gas flowdividing portion in a predetermined length in a longitudinal directionof the vehicle and thereby connecting front and rear end portions of thegas flow dividing portion to front and rear walls, that are arranged inthe longitudinal direction of the vehicle, of the airbag, and disposingthe inflator at an upper end portion or lower end portion of the airbagas viewed in the vertical direction of the vehicle, and directing thegas flow from the inflator in a vertical direction of the vehicle, andforming the gas flow dividing portion in a mountain shape whichprotrudes against the gas flow from the inflator.
 10. The inflating anddeploying method of an airbag according to claim 9, characterized inthat: the dividing portion is formed and arranged so as to protrude in aV-shape.
 11. The inflating and deploying method of an airbag accordingto claim 9, characterized in that: the dividing portion is formed andarranged so as to protrude in a U-shape.
 12. The inflating and deployingmethod of an airbag according to claim 9, characterized by furthercomprising the step of: connecting between one area and an other areawithin the airbag, both areas being separated by the gas flow dividingportion.